Re: [Qemu-devel] [PATCH 03/17] savevm: Implement VMS_DIVIDE flag

[David Gibson]

On Tue, Jul 09, 2013 at 09:06:21AM -0500, Anthony Liguori wrote:
> David Gibson <address@hidden> writes:
> 
> > On Mon, Jul 08, 2013 at 01:27:05PM -0500, Anthony Liguori wrote:
> >> Alexey Kardashevskiy <address@hidden> writes:
> >> 
> >> > From: David Gibson <address@hidden>
> >> >
> >> > The vmstate infrastructure includes a VMS_MULTIPY flag, and associated
> >> > VMSTATE_VBUFFER_MULTIPLY helper macro.  These can be used to save a
> >> > variably sized buffer where the size in bytes of the buffer isn't 
> >> > directly
> >> > accessible as a structure field, but an element count from which the size
> >> > can be derived is.
> >> 
> >> Why?  What's the point of sending the total size vs. the element
> >> count?
> >
> > Because it's more convenient to work with the total size at runtime,
> > and because the VMSTATE stuff works with actual structure fields,
> > there's not really a way to convert it at migrate time, short of this.
> 
> The only thing I see using it is the tce array which is broken
> anyway.

It's only broken due to a bug elsewhere.  Whatever is done there it
will still be some sort of VBUFFER arrangement, and the window will
still be a more convenient thing to work with than the number of
entries.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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